Chemistry Revision: Rates of reaction

Chemistry Revision: Reversible Reactions

Key KnowledgeTWO equations for calculating rate of reaction:

Mean R of R = quantity of reactant usedTime taken

Mean R of R = quantity of product formedTime taken

Units for rate of reaction:(a) Cm3/s(b) g/s

5 factors that affect rate of reaction:1) Catalyst2) Temperature3) Concentration4) Surface area5) Pressure (in gases)

Define: Activation energy: Minimum amount of energy that particles must have to react

Catalyst: provide a different pathway for a reaction that has a lower activation energy. Is not used up in the reaction.

According to collision theory, particles must collide with enough energy to react.

Draw a reaction profile for a reaction with and without a catalyst.

Mastery Matrix PointsCalculate the mean rate of reaction Recall the units for mass (g), volume (cm3) and rate (g/s, cm3/s, mol/s)Draw tangents on curves in order to calculate rates of reactionExplain the collision theory and link to activation energyDescribe and explain factors that affect rates of reaction (concentration, pressure, surface area, catalysts and temperature)Plot and interpret graphs showing rates of reactionExplain why one reactant is used in excess in a chemical reactionDescribe what is meant by ‘a limiting reactant’RP Rates of Reaction: Investigate how changes in concentration affect the rates of reactions by measuring volume of the gas and change of colourGive examples of catalysts Draw a reaction profile for a catalysed reaction

Time (s) Volume of CO2 (cm3)

0 010 1020 1830 2440 3050 3560 3870 4080 4190 41100 41

2. a) Plot the graph to show these results. (b) Use it to calculate the rate of reaction at 15 seconds. 8cm/20s (using a tangent) = 0.4cm/s

(c) describe AND explain the pattern shown by the results. As time increases, the volume of gas increases at a decreasing rate. This is because the reactants get used up so there are less frequent collisions.

3. Describe AND explain the effect of the 4 factors on rate of reaction:(a) Concentration: As concentration increases, rate of reaction increases. This is because there are more particles so there will be more collisions between particles. This will increase the rate of reaction.(b) Temperature: As temperature increases, rate of reaction increases. This is because the particles have more kinetic energy so more collisions are successful. This will increase the rate of reaction.(c) Surface area: As surface area increases (it is broken into smaller pieces), rate of reaction increases. This is because more particles are exposed and able to collide. This leads to more collisions and therefore will increase the rate of reaction.(d) Catalyst: This provides an alternative pathway for the reaction with a lower activation energy. This means that more particles collide with sufficient energy so there are more successful collisions and therefore rate of reaction increases.

1. In a reaction, 24cm3 of hydrogen gas is produced in 2 minutes. Calculate the rate of reaction. 24cm3/ 120= 0.2cm3/s

2. Calculate rate of reaction AND write the word and symbol equation in each of these scenarios:(a) Sarah is reacting calcium carbonate with hydrochloric acid. She times

how much gas is produced in 2 minutes 30 using a gas syringe. She find that 45cm3 of gas is produced in this time. 45cm3/ 120= 0.38cm3/s

Calcium carbonate + hydrochloric acid -> calcium chloride + carbon dioxide + water

CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + CO2 (g) + H2O (l)

(b) Linda reacts 5g of magnesium with sulphuric acid. It takes 5 minutes for the magnesium to have reacted completed. Calculate the rate of reaction. 5g / 300s= 0.017g/s Magnesium sulphate + hydrogen Magnesium sulfate + hydrogenMg (s) + H2SO4 (aq) -> MgSO4 (aq) + H2 (g)

Key Knowledge

Define:Reversible reactions: The products react to produce the original reactants

Mastery Matrix Points

Use the appropriate symbol to denote a reversible reactionExplain energy changes in reversible reactions (ammonium chloride and hydrated copper sulphate)Explain what is meant by the term ‘equilibrium’

1. a) We can represent reversible reactions with an equation. Complete this equation below by adding in the correct type of

Key Knowledge

Define:Reversible reactions: The products react to produce the original reactants1. a) We can represent reversible reactions with an equation. Complete this equation below by adding in the correct type of

Chemistry Revision: The Earth’s Early Atmosphere

Chemistry Revision: Global warming

Key KnowledgeState the 4 gases present in the Early Atmosphere 4.6 billion years ago:

70 % of Carbon dioxide 10 % of Methane 10% of Ammonia10% of Water Vapour

The atmosphere was very similar to the current atmosphere on two other planets MARS and VENUS. The majority of these gases are thought to have been produced by VOLCANIC ACTIVITY

Earth today, name the 2 most prevalent gases: 80% of NITROGEN20 % of OXYGEN(Very small amounts of CARBON DIOXIDE0.04%)

Name the process by which oceans are thought to have formed: CONDENSATION

The process which caused oxygen levels to increase was PHOTOSYNTHESIS. This was carried out by PLANTS and algae.

Mastery Matrix Points Describe the composition of the atmosphere and how long this has been the caseDescribe the development from early atmosphere to present dayDraw links between the early Earth’s atmosphere and that of other planets (Mars and Venus)Evaluate different theories regarding the Earth’s early atmosphereExplain why oxygen levels increased and carbon dioxide levels decreased (linking to photosynthesis and sedimentation)

Understanding and Explaining1. Write the word and balanced symbol equation for photosynthesis.

2. Compare and contrast the composition of the current atmosphere to that of the atmosphere 4.6 billion years ago. Early Atmosphere (4.6 billion years ago) Present atmosphereVery little nitrogen 80% Nitrogen

Very little oxygen! 20% Oxygen

70% Carbon dioxide 0.04% carbon dioxide

10% Water vapour, methane and ammonia VERY small amounts of water vapour, methane and ammonia

3. The current atmosphere contains significantly more oxygen than the early atmosphere. Explain why by completing the paragraph and using the key words below: 2.7 billion years ago, green PLANTS and ALGAE- started to evolve. These organisms absorb CARBON DIOXDE and produce OXYGEN in a process called PHOTOSYNTHESIS.Photosynthesis Algae Plants Carbon dioxide Oxygen

4. The current atmosphere contains significantly less carbon dioxide than the early atmosphere. State the 4 ways that is thought to have led to this decrease:

1. - Sedimentation (forming sedimentary rocks)2. - Formation of fossil fuels3. - Dissolving in the oceans4. - Photosynthesis

Key KnowledgeName the 3 main greenhouse gases:- water vapour - methane- carbon dioxide

Mastery Matrix Points Describe the term ‘greenhouse gases’ and give three examples (water vapour, carbon dioxide and methane)Describe the ‘greenhouse effect’ linking to the wavelength of radiationDescribe the effect of human activities on the levels of greenhouse gases, recalling two that affect methane and two that affect carbon dioxideExplain how peer review evidence have linked these activities to global climate changeExplain why it is difficult to model this and how this has led to simplification, speculation and biased opinions in the mediaDescribe 4 potential effects of global climate change

Chemistry Revision: Air Pollution and finite resources

Key KnowledgeName the 3 main greenhouse gases:- water vapour - methane- carbon dioxide

Mastery Matrix Points Describe the term ‘greenhouse gases’ and give three examples (water vapour, carbon dioxide and methane)Describe the ‘greenhouse effect’ linking to the wavelength of radiationDescribe the effect of human activities on the levels of greenhouse gases, recalling two that affect methane and two that affect carbon dioxideExplain how peer review evidence have linked these activities to global climate changeExplain why it is difficult to model this and how this has led to simplification, speculation and biased opinions in the mediaDescribe 4 potential effects of global climate change

Understanding and Explaining1. Complete the paragraph by using the key words below: The waves entering the atmosphere from the sun are made up of SHORT wavelength radiation that is easily able to pass through the atmosphere. Some of this is ABSORBED by the surface of the Earth whilst some is RELFECTED as LONGER wavelength radiation. This cannot pass through the atmosphere and so more is reflected back to the earth’s surface or absorbed causing the atmosphere to INCREASE in temperature.

Increase short absorbed longer reflected

2. Explain why we need some greenhouse gases in our atmosphere.We need some greenhouse gases in our atmosphere as it would be too cold for water to be a liquid so living things would not be able to survive.

3. Use the graph to describe the average global temperature between 1860and today.

Global average temperature has generally increased between 1860 and today.1860 = 13.5⁰C and today 14.6⁰C.Increase of 1.1⁰C.It has fluctuated between these two dates.

Key Knowledge

One of the biggest sources of atmospheric pollution is combustion of fuels.

Five gases released into the atmosphere when

Mastery Matrix Points Describe combustion as a major source of atmospheric pollutionName gases release when fuels such as coal are burnt (carbon dioxide, water vapour, carbon monoxide, sulphur dioxide and nitrogen oxides) and predict which of these would be produced from a given fuel compositionDescribe ‘particulates’ Describe issues arising from carbon dioxide, sulphur dioxide, nitrogen oxides and particulatesRecalls that humans use the Earth’s resources to provide; warmth, shelter, food, transport (through timber, clothing, fuels/energy and other materials) Define what is meant by the term ‘finite resource’

Key Knowledge

One of the biggest sources of atmospheric pollution is combustion of fuels.

Five gases released into the atmosphere when

Mastery Matrix Points Describe combustion as a major source of atmospheric pollutionName gases release when fuels such as coal are burnt (carbon dioxide, water vapour, carbon monoxide, sulphur dioxide and nitrogen oxides) and predict which of these would be produced from a given fuel compositionDescribe ‘particulates’ Describe issues arising from carbon dioxide, sulphur dioxide, nitrogen oxides and particulatesRecalls that humans use the Earth’s resources to provide; warmth, shelter, food, transport (through timber, clothing, fuels/energy and other materials) Define what is meant by the term ‘finite resource’

Chemistry Revision: Life cycle assessments,waste and water

Key KnowledgeLife cycle assessments (LCAs) are carried out to assess the environmental impact of products.

Name the 4 stages that must be evaluated during an LCA.1) Extracting/processing raw materials

2) Manufacturing/packing

3) Use

4) Disposal (inc. transport)Define ‘potable’: Water that is safe to drink (it is NOT pure water!)Two steps in producing potable water from ground (rain/fresh) water?

1) Filter (to remove any solid particles)

2) sterilise (to kill any microbes)

Three substances that can be used to sterilise water:1. - Oxone2. -Chlorine3. -UV light

Two steps of desalination of salty water?1) Heat and evaporate water2) Cool water vapour and condense to form pure

water

Two substances that must be removed from waste water from agriculture and sewage?1) Harmful microorganisms2) Organic materialTwo substances that must be removed from industrial waste water?1) Organic material2) Harmful chemicals

Mastery Matrix Points Describe the 4 stages of a life cycle assessmentUse data to carry out LCA for shopping bags made from plastic and paperExplain how we can reduce our use of limited resources (reduce, reuse, recycle)Describe the properties of potable water (is safe to drink) linking to purity, salt and microbe levels Describe the different sources of drinking water in the UK and the process that it must undergo before it is potableDescribe the process of desalination (distillation or reverse osmosis)Evaluate the methods to produce potable water (linking to location and potential water supply)RP Water Purification: Analyse and purify water samples from different sources, including pH, dissolved solids and distillationExplain what needs to be removed from sewage and agricultural waste in comparison with industrial waste water Describe the 4 steps of sewage treatment

1. Use the information below to carry out a simple LCA for plastic and paper shopping bags. Use this to decide which is better for us to use and why. The number indicates the relative quantities e.g. paper bags require 4 times more water during their entire life time.

Conclusion: I think the plastic/ paper bag is better for us to use because ….conclusion must be supported by statements given above. E.g I think the plastic bag is better because it uses less non-renewable energy, water and produces less solid waste which means less impact on the earth’s natural resources

2. Describe the 4 stages of treating sewageScreening and grit removal, sedimentation to produce sewage sludge and effluent, anaerobic digestion of sewage sludge (solid bit), aerobic biological treatment of effluent.

3. Fill in the table for the results you would expect when testing salt and distilled water:Distilled water – flame test – no colour change/ nitric acid – no colour change/precipitateSalt water – Flame test – yellow – sodium ions present/ nitric acid – white precipitate chloride ions present

Plastic Paper Statement comparing plastic and paper bagsConsumption of non-renewable energy

1 1.1 Plastic bags use slightly less non- renewable energy, meaning less drain on earth’s natural resources

Consumption of water

1 4 Plastic bags use ¼ less water during production which is less of a drain on earth’s natural resources

Green house gas emissions

1 3.3 Making plastic bags produces approximately 1/3 less greenhouse gases, which means there is less contribution to global warming

Solid waste produced

1 1.7 Plastic bags produce around ½ the solid waste that paper bags do meaning that less landfill space will be taken up during their production

Average number of uses

10 2 Plastic bags are more hard wearing and will need to be replaced less often. Paper bags need to be replaced 5x over the lifetime of a plastic bag

Years taken to biodegrade

25 2 Plastic bags take a very long time to degrade ( around 12-13 times longer than paper bags). This means they will take up more landfill space and become and eye sore